Climate Change Impacts on Hydrology of the Western Cascades

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1 Climate Change Impacts on Hydrology of the Western Cascades Marketa M. Elsner UW Climate Impacts Group Mt Baker - Snoqualmie National Forest Climate Change Workshop April 28, 2011

2 We care about climate and hydrologic change because: we have growing, and often competing, water demands changes in water balance are closely linked with other impact pathways (forest & aquatic ecosystems, recreation, infrastructure)

3 Our primary mechanism for storing water snow is sensitive to warming. The Cascade and Olympic Mountains have the highest fraction of warm snow (snow falling between F) in the continental U.S. (Mote et al. 2008)

4 Looking Forward Projected changes in 21 st century climate and hydrology

5 Projected Increases in Annual PNW Temperature * Relative to average 2020s 2040s 2080s +2.0 F ( F) +3.2 F ( F) +5.3 F ( F) Historic C F Mote and Salathé, 2009

6 Projected Increases in Annual PNW Precipitation * Relative to average 2020s +1% (-9 to 12%) 2040s +2% (-11 to +12%) 2080s +4% (-10 to +20%) Historic Mote and Salathé, 2009

7 While there is significant variability across models, we anticipate wetter winters and drier summers Mote and Salathé, 2009

8 Recession of Whitechuck Glacier (Sauk Headwaters) North Cascades Glacier Climate Project (NCGCP) Photos courtesy of Dr. Mauri Pelto, Nichols College

9 Loss of glacial mass may increase summer flow in the short term and decrease summer flow in the long term.

10 B1 A1B Key Impact: Loss of April 1 Snow Cover Map: Rob Norheim 2020s 2040s 2080s Projections compared to average Spring snowpack is projected to decline as more winter precipitation falls as rain rather than snow, especially in warmer mid-elevation basins. Also, snowpack will melt earlier with warmer spring temperatures

11 Key Impact: Shift in Hydrologic Basin Types Historically snow dominated watersheds in the eastern Cascades will slowly shift toward becoming transient watersheds (blue to red). Map: Rob Norheim

12 Elsner et al Naturalized flows (i.e., no dams) Impacts to Seasonal Streamflow Timing Skykomish River near Gold Bar Skagit River at Mt Vernon Increasing winter flows Earlier, lower peak runoff Lower summer streamflow Mix Rain/Snow Transient Basin Snow Dominant Basin

13 The Columbia Basin Climate Change Scenarios Project A comprehensive suite of free 21 st century hydro/climate scenarios for almost 300 sites in the PNW, including data for: streamflow evapotranspiration flood & low flow statistics precip, temp soil moisture snowpack

14 Skykomish River near Gold Bar Historical Future Projections - mean Future Projections - range Data source: CIG,

15 Flow Soil Moisture

16 Changes in Hydrologic Extremes Dec 2007 Flood Damage Sauk River near Darrington Cedar River at Chester Morse Lake during extreme low flows

17 2040s Changes in Flood Risk Skykomish River near Gold Bar A1B (medium scenario): Central tendency of hybrid delta scenarios is: 21% increase Range of increase is 9% to 55% Projected 20, 50, 100-year floods using different downscaling techniques B1 (low scenario): Central tendency of hybrid delta scenarios is: 14% increase Range is decrease of 14% to increase of 40% Historical Hybrid Delta Projections Traditional Delta Projections Data source: CIG,

18 2040s Changes in Low Flows Skykomish River near Gold Bar A1B (medium scenario): Central tendency (hybrid delta scenarios) is: 27% decrease Range of decrease is 17% to 36% Projected 7Q10 low flow using different downscaling techniques B1 (low scenario): Central tendency (hybrid delta scenarios) is: 22% decrease Range of decrease is 8% to 34% 7Q10: 7-day consecutive low flow with a 10-year recurrence interval Historical Hybrid Delta Projections Traditional Delta Projections Data source: CIG,

19 Looking Forward Related Impacts

20 Aquatic Ecosystem Impacts Mantua, N., I. Tohver, A.F. Hamlet, 2010: Climate change impacts on streamflow extremes and summertime stream temperature and their possible consequences for freshwater salmon habitat in Washington State, Climatic Change, online first, doi: /s

21 Stormwater Management Index-Galena Rd November 2006 Example Application: Improving Estimates of the 100-year Flood Olympic National Forest

22 Forest Access Mountain Loop Highway 8.6mi east of Verlot Ranger Station Jan 2011

23 Forest fire training at Skagit Civilian Cons. Corps camp, Mt. Baker National Forest, Washington Littell, J.S., E.E. Oneil, D. McKenzie, J.A. Hicke, J.A. Lutz, R.A. Norheim, and M.M. Elsner Forest ecosystems, disturbance, and climatic change in Washington State, USA. Climatic Change 102(1-2): , doi: /s x Forest Disturbance Projected Area Burned in WA Crystal Mine Fire Aug 2009 Snoqualmie Ranger District

24 Sediment Impacts

25 Increased Landslide Risks

26 Marketa McGuire Elsner UW Climate Impacts Group

27 Entiat River Basin Fine Scale Projections (100m) A1B In collaboration with the USFS PNW Research Station SWE ET Flow Depth Streamflow units: cfs Units:mm unless otherwise noted

28 Exploring the Effects of Climate Change on Vegetation Disturbance and Recovery Processes Limited veg recovery on south-facing slope Improve soil depth map Overlay maps of soil moisture stress (from hydrology model) and aerial photos Determine whether regeneration patterns coincide with patterns of soil moisture stress If a relationship is established, how might climate change impact vegetation recovery Strong veg recovery on south-facing slope Some regions without forest regeneration